What happens if you drink tea brought as a gift from unknown vendor in india?

Who bought it ? Who brought you the tea is important. Does he/she know and tasted this particular tea ? Go to a local gourmet specialist to identify it. Some vendors in street markets may not label/brand what they sell . Good luck !
Mgt/advice. The water is boiled first and this process kills many germs. If you develop an illness within a few hours, please stay well hydrated and eat bananas/yogurt. If you are referring to tea leaves and then you made the tea here in the U.S. it should not be a problem. There are many companies that produce tea for export/gifts.